How much trust in gas gauge

thinkxingu · 05-14-2016, 08:34 AM

Hi! How much faith do y'all place in your gas gauges? I know they can waiver with movement, but are they fairly reliable when stable? What's a good level to be running down to?

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VitaBene · 05-14-2016, 09:54 AM

Mine seems to be pretty accurate sitting or on plane. Check yours by filling when showing half, then calculate actual from used. Then fill at 1/4 and check. I try to stay at a quarter min.

I rarely fill to save weight. Gas weighs 6 lbs per gallon, so for me I save 300 pounds by not filling.

thinkxingu · 05-14-2016, 09:55 AM

Quote:

Originally Posted by VitaBene

Mine seems to be pretty accurate sitting or on plane. Check yours by filling when showing half, then calculate actual from used. Then fill at 1/4 and check. I try to stay at a quarter min.

I rarely fill to save weight. Gas weighs 6 lbs per gallon, so for me I save 300 pounds by not filling.

Good ideas, thanks!

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Slickcraft · 05-14-2016, 10:34 AM

After a few fill-ups I calculate an average number of gallons/hour for our usage and then go by hours since last fill.

I also have noted the # gallons for a fill and the gauge level prior to the fill. I found that the gauge overstates the remaining fuel.

DesertDweller · 05-14-2016, 11:25 AM

To answer your question, some gauges are a lot more accurate than others. For me, mine is fine when stationary but once I get up on plane it drops off like there is no gas it in. I also follow the quarter tank policy. Once it gets to a quarter tank I will put gas in it.

Descant · 05-14-2016, 12:12 PM

Part of the accuracy may depend on the shape of the tank. Old round tanks would stay at 1/2 full forever and as you got to the round bottom, the gauge dropped quickly. Also depends on "usable" fuel i.e. how far off the bottom is your pick up? Varies from mfg to mfg.

I used to ad fuel at 1/4 and fill to 3/4 depending on cruising plans. That kept the weight down and leveled the spending pattern. A few years ago, the marina manager said that's what most people did. Then people started filling all the way to get as much fuel on board as possible before the next price increase, and they cruised less, anchored more.

I also had a time frame where the gauge didn't work, so as Slickcraft suggests, I watched the hour meter.

My father used to own a 1950 CC 30' Cruiser. No gauges, no hour meter, but the tank fill was a straight pipe and we had a measuring dipstick. Marine gas was $0.35/gallon, I think, and the friend who said "Let me pay for the gas" wandered off as the pump went above $15.00.

noreast · 05-14-2016, 01:14 PM

The good news is they usually read less than you have,or at least my last few have, I was way low a few times and actually had at least 5 gallons left.

thinkxingu · 05-14-2016, 02:20 PM

Filled up at half today and took 20 gallons, which echos the post above about reading over (we have a 42 gallon tank). Looks like I'm good down to 1/4 tank. Thanks!

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NoBozo · 05-14-2016, 03:23 PM

I had a 20 foot Donzi with a 350 SBC that burned 3.5-4.0 GPH at cruise and just putting around. One of my very first trips ended.. Out of Gas after dark and a mile from the ramp. Wilderness on shore. Picture two guys with canoe paddles paddling for a couple of hours...one guy on each side of the rear seat hanging over the side. Good thing we had beer....and canoe paddles.

The gas gauge was about HALF with the needle "bobbing".

From then on I kept close track of the hour meter at all times, and I kept a log book of how many gallons I added at each refueling. Generally I would start thinking about the gas dock when the gauge needle got down to 3/4 mark with the needle "bobbing'. With a full tank the needle would stay pegged for quite awhile (hours) before bobbing down toward 3/4. At that point: "Lets go for gas."

NB

PS: I never ran out of gas again.

Dave R · 05-14-2016, 07:04 PM

I removed the gas gauge on my boat and put a Lowrance LMF200 in place of it. I also put in a fuel flow probe a a spoeed sensor. Now I have a ridiculously accurate gas gauge and I can see my actual MPG in real time so I can can tweak my throttle and trim to maximize fuel economy. Very handy on long trips.

upthesaukee · 05-14-2016, 09:20 PM

I fill up at half a tank. When I am at the dock, the gauge appears to be pretty accurate.

Why at half a tank, you might ask. With my Sunbeam Corsair, with a 135 Optimax, I had a 30 Gal tank, but I had Smartgauges, and the fuel flow was quite accurate. I used to run down to 20-22 gallons used, then head for the marina to fill up.

We got Upthesaukee Too, with a 58 gallon tank. When we got the boat, it had "some" gas in it. Looked like just under a half. We went out a few times, and decided to stop at West Alton to get gas on our way back to Parker's; gauge was just under a quarter tank. Gas at the time was up around $4 / gal. . It took 53 gallons. My wife gulped. We had a spell of nice weather, and used the boat quite a bit, and took it for a pretty good ride, and on the way home, we came to a stop in the middle of the lake to enjoy the day, and saw that it was again under a quarter tank. Had just enough time to make it to West Alton and filled up again. 49 gallons. Two $200 (roughly) fill ups in two weeks.

We got away from the gas dock, and my wife said we need to start filling up when we get down to half a tank; then it will only be $100 per fill-up. I told her that it didn't matter: filling up at 50 gallons every 2 weeks for $200 or every week or so at around 25 gallons for $100. She said that she didn't care...she just didn't want to see the $200 fill-ups. I said OK Admiral... because as we all know, a happy wife is a happy life.

Kamper · 05-15-2016, 12:24 PM

I used portable tanks and calculated my burn at 5gph full-out. My fuel-gauge was my watch. A lot of people use this technique even if they also have more sophisticated equipment.

itchin for fishin · 05-20-2016, 07:02 PM

I just went through that today. I had a boat on dry dock last summer and still had a 1/2 tank of fuel that I wanted to burn off before refueling. When I got to a 1/4 tank I called it quits since I once went below the quarter, and to my embarrassment, I ran out of gas as I went through Spindle Point. So long answer to short question, I trust it to a 1/4 tank.

joey2665 · 05-22-2016, 10:16 AM

I have a brand new Sea Ray and Irwin told me the gas gauges even with new technology are off by at least 25%. I never go under 1/3 of a tank

SAB1 · 05-23-2016, 03:39 PM

I tend to fill up when it drops a little under half, especially as the weather cools toward fall. Try to minimize condensation.

Bear Islander · 05-23-2016, 04:10 PM

My gauge stays at full until the tank is about half empty. I think the tank is at an angle. When it indicates below 1/4 I am almost empty. I fill up when it goes under 1/2.

Phantom · 05-23-2016, 04:11 PM

Quote:

Originally Posted by Bear Islander

My gauge stays at full until the tank is about half empty. I think the tank is at an angle. When it indicates below 1/4 I am almost empty. I fill up when it goes under 1/2.

Have everyone sit on the other side of the boat ?

.

05-14-2016, 08:34 AM	#1
thinkxingu Senior Member Join Date: Jul 2014 Posts: 6,323 Thanks: 1,174 Thanked 2,096 Times in 1,297 Posts	How much trust in gas gauge Hi! How much faith do y'all place in your gas gauges? I know they can waiver with movement, but are they fairly reliable when stable? What's a good level to be running down to? Sent from my XT1528 using Tapatalk

05-14-2016, 09:54 AM	#2
VitaBene Senior Member Join Date: Jul 2007 Location: Moultonborough Posts: 3,596 Thanks: 1,642 Thanked 1,641 Times in 844 Posts	Relatively Mine seems to be pretty accurate sitting or on plane. Check yours by filling when showing half, then calculate actual from used. Then fill at 1/4 and check. I try to stay at a quarter min. I rarely fill to save weight. Gas weighs 6 lbs per gallon, so for me I save 300 pounds by not filling.

05-14-2016, 12:12 PM	#6
Descant Senior Member Join Date: Mar 2006 Location: Merrimack and Welch Island Posts: 4,413 Thanks: 1,365 Thanked 1,636 Times in 1,068 Posts	Fill up? Part of the accuracy may depend on the shape of the tank. Old round tanks would stay at 1/2 full forever and as you got to the round bottom, the gauge dropped quickly. Also depends on "usable" fuel i.e. how far off the bottom is your pick up? Varies from mfg to mfg. I used to ad fuel at 1/4 and fill to 3/4 depending on cruising plans. That kept the weight down and leveled the spending pattern. A few years ago, the marina manager said that's what most people did. Then people started filling all the way to get as much fuel on board as possible before the next price increase, and they cruised less, anchored more. I also had a time frame where the gauge didn't work, so as Slickcraft suggests, I watched the hour meter. My father used to own a 1950 CC 30' Cruiser. No gauges, no hour meter, but the tank fill was a straight pipe and we had a measuring dipstick. Marine gas was $0.35/gallon, I think, and the friend who said "Let me pay for the gas" wandered off as the pump went above $15.00.

05-14-2016, 09:20 PM	#11
upthesaukee Senior Member Join Date: Jan 2003 Location: Alton Bay Posts: 5,604 Blog Entries: 2 Thanks: 2,469 Thanked 1,983 Times in 1,083 Posts	I fill up at half a tank. I fill up at half a tank. When I am at the dock, the gauge appears to be pretty accurate. Why at half a tank, you might ask. With my Sunbeam Corsair, with a 135 Optimax, I had a 30 Gal tank, but I had Smartgauges, and the fuel flow was quite accurate. I used to run down to 20-22 gallons used, then head for the marina to fill up. We got Upthesaukee Too, with a 58 gallon tank. When we got the boat, it had "some" gas in it. Looked like just under a half. We went out a few times, and decided to stop at West Alton to get gas on our way back to Parker's; gauge was just under a quarter tank. Gas at the time was up around $4 / gal. . It took 53 gallons. My wife gulped. We had a spell of nice weather, and used the boat quite a bit, and took it for a pretty good ride, and on the way home, we came to a stop in the middle of the lake to enjoy the day, and saw that it was again under a quarter tank. Had just enough time to make it to West Alton and filled up again. 49 gallons. Two $200 (roughly) fill ups in two weeks. We got away from the gas dock, and my wife said we need to start filling up when we get down to half a tank; then it will only be $100 per fill-up. I told her that it didn't matter: filling up at 50 gallons every 2 weeks for $200 or every week or so at around 25 gallons for $100. She said that she didn't care...she just didn't want to see the $200 fill-ups. I said OK Admiral... because as we all know, a happy wife is a happy life. __________________ I Live Here... I am always UPTHESAUKEE !!!!

05-22-2016, 10:16 AM	#14
joey2665 Senior Member Join Date: Sep 2008 Location: Meredith Bay & LI, NY Posts: 3,222 Thanks: 1,219 Thanked 1,009 Times in 649 Posts	Off by at least 25% I have a brand new Sea Ray and Irwin told me the gas gauges even with new technology are off by at least 25%. I never go under 1/3 of a tank

05-14-2016, 10:34 AM	#4
Slickcraft Senior Member Join Date: Mar 2008 Location: Welch Island and The Taylor Community Posts: 3,318 Thanks: 1,233 Thanked 2,103 Times in 960 Posts	After a few fill-ups I calculate an average number of gallons/hour for our usage and then go by hours since last fill. I also have noted the # gallons for a fill and the gauge level prior to the fill. I found that the gauge overstates the remaining fuel.

05-14-2016, 11:25 AM	#5
DesertDweller Senior Member Join Date: Aug 2011 Location: Las Vegas, NV and Moultonborough, NH Posts: 384 Thanks: 26 Thanked 88 Times in 74 Posts	To answer your question, some gauges are a lot more accurate than others. For me, mine is fine when stationary but once I get up on plane it drops off like there is no gas it in. I also follow the quarter tank policy. Once it gets to a quarter tank I will put gas in it.

05-14-2016, 01:14 PM	#7
noreast Senior Member Join Date: Mar 2015 Posts: 648 Thanks: 316 Thanked 120 Times in 93 Posts	The good news is they usually read less than you have,or at least my last few have, I was way low a few times and actually had at least 5 gallons left.

05-14-2016, 02:20 PM	#8
thinkxingu Senior Member Join Date: Jul 2014 Posts: 6,323 Thanks: 1,174 Thanked 2,096 Times in 1,297 Posts	Filled up at half today and took 20 gallons, which echos the post above about reading over (we have a 42 gallon tank). Looks like I'm good down to 1/4 tank. Thanks! Sent from my XT1528 using Tapatalk

05-14-2016, 03:23 PM	#9
NoBozo Senior Member Join Date: Jun 2008 Location: Portsmouth. RI Posts: 2,231 Thanks: 400 Thanked 460 Times in 308 Posts	I had a 20 foot Donzi with a 350 SBC that burned 3.5-4.0 GPH at cruise and just putting around. One of my very first trips ended.. Out of Gas after dark and a mile from the ramp. Wilderness on shore. Picture two guys with canoe paddles paddling for a couple of hours...one guy on each side of the rear seat hanging over the side. Good thing we had beer....and canoe paddles. The gas gauge was about HALF with the needle "bobbing". From then on I kept close track of the hour meter at all times, and I kept a log book of how many gallons I added at each refueling. Generally I would start thinking about the gas dock when the gauge needle got down to 3/4 mark with the needle "bobbing'. With a full tank the needle would stay pegged for quite awhile (hours) before bobbing down toward 3/4. At that point: "Lets go for gas." NB PS: I never ran out of gas again.

05-14-2016, 07:04 PM	#10
Dave R Senior Member Join Date: Jul 2004 Posts: 2,985 Thanks: 246 Thanked 744 Times in 444 Posts	I removed the gas gauge on my boat and put a Lowrance LMF200 in place of it. I also put in a fuel flow probe a a spoeed sensor. Now I have a ridiculously accurate gas gauge and I can see my actual MPG in real time so I can can tweak my throttle and trim to maximize fuel economy. Very handy on long trips.

The Following 4 Users Say Thank You to upthesaukee For This Useful Post:
Just Sold (05-14-2016), radiocontester (05-14-2016), thinkxingu (05-15-2016), Winnisquamer (05-15-2016)

05-15-2016, 12:24 PM	#12
Kamper Senior Member Join Date: Jul 2005 Location: Thornton's Ferry Posts: 1,308 Thanks: 67 Thanked 172 Times in 128 Posts	I used portable tanks and calculated my burn at 5gph full-out. My fuel-gauge was my watch. A lot of people use this technique even if they also have more sophisticated equipment.

05-20-2016, 07:02 PM	#13
itchin for fishin Senior Member Join Date: Jul 2004 Posts: 105 Thanks: 3 Thanked 2 Times in 1 Post	I just went through that today. I had a boat on dry dock last summer and still had a 1/2 tank of fuel that I wanted to burn off before refueling. When I got to a 1/4 tank I called it quits since I once went below the quarter, and to my embarrassment, I ran out of gas as I went through Spindle Point. So long answer to short question, I trust it to a 1/4 tank.

05-23-2016, 03:39 PM	#15
SAB1 Senior Member Join Date: Feb 2012 Location: Tuftonboro Posts: 1,243 Thanks: 192 Thanked 329 Times in 239 Posts	I tend to fill up when it drops a little under half, especially as the weather cools toward fall. Try to minimize condensation.

05-23-2016, 04:10 PM	#16
Bear Islander Senior Member Join Date: Apr 2004 Location: Bear Island Posts: 1,764 Thanks: 32 Thanked 441 Times in 207 Posts	My gauge stays at full until the tank is about half empty. I think the tank is at an angle. When it indicates below 1/4 I am almost empty. I fill up when it goes under 1/2.